1. Field of the Invention
The present invention relates generally to a grinding machine and more particularly to a grinding machine with a rest apparatus for supporting a workpiece.
2. Description of the Prior Art
In the prior art for grinding a workpiece by using a rest apparatus, a grinding operation has been performed in such a manner that the rest apparatus is advanced toward the workpiece at a slightly faster rate than the advancing speed of a grinding wheel after the grinding wheel has advanced to a predetermined position, and wherein the grinding wheel grinds the workpiece on the condition that the rest apparatus is in contact with the workpiece.
According to such prior method, because the rest apparatus is initially in contact with a workpiece which has not been ground to sufficiently acceptable roundness and a grinding operation is finished on the condition that the rest apparatus is in contact with the workpiece, the original out of roundness of the workpiece affects the final roundness of the finished workpiece and creates an external configuration which deviates from the true center thereof. Because the advancing speed of the rest apparatus is slightly faster than that of the grinding wheel, significant deflection is given to the workpiece by the rest apparatus.
Such excess deflection causes the workpiece to be ground with an external configuration which deviates from the true center thereof.